package com.ruoyi.common.utils.bean;

import com.baomidou.mybatisplus.core.toolkit.support.SFunction;
import org.springframework.util.ClassUtils;
import org.springframework.util.ReflectionUtils;

import java.beans.Introspector;
import java.lang.invoke.SerializedLambda;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Collection;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

/**
 * @Classname ReflectionUtil
 * @Author: sunluquan
 * @Date: 2021/7/16 19:39
 * @Description TODO
 */
public class ReflectionUtil {

    private static Map<SFunction<?, ?>, Field> cache = new ConcurrentHashMap<>();

    public static <T, R> Set<String> getFieldNames(Collection<SFunction<T, R>> sFunctions) {
        Set<String> fieldNames = new HashSet<>(sFunctions.size()+1);

        for (SFunction<T, R> trSFunction : sFunctions) {
            fieldNames.add(getFieldName(trSFunction));
        }
        return fieldNames;
    }
    public static <T, R> String getFieldName(SFunction<T, R> SFunction) {
        Field field = ReflectionUtil.getField(SFunction);
        return field.getName();
    }
    public static Field getField(SFunction<?, ?> sFunction) {
        return cache.computeIfAbsent(sFunction, ReflectionUtil::findField);
    }
    public static Field findField(SFunction<?, ?> sFunction) {
        Field field = null;
        String fieldName = null;
        try {
            // 第1步 获取SerializedLambda
            Method method = sFunction.getClass().getDeclaredMethod("writeReplace");
            method.setAccessible(Boolean.TRUE);
            SerializedLambda serializedLambda = (SerializedLambda) method.invoke(sFunction);
            // 第2步 implMethodName 即为Field对应的Getter方法名
            String implMethodName = serializedLambda.getImplMethodName();
            if (implMethodName.startsWith("get") && implMethodName.length() > 3) {
                fieldName = Introspector.decapitalize(implMethodName.substring(3));

            } else if (implMethodName.startsWith("is") && implMethodName.length() > 2) {
                fieldName = Introspector.decapitalize(implMethodName.substring(2));
            } else if (implMethodName.startsWith("lambda$")) {
                throw new IllegalArgumentException("SerializableSFunction不能传递lambda表达式,只能使用方法引用");

            } else {
                throw new IllegalArgumentException(implMethodName + "不是Getter方法引用");
            }
            // 第3步 获取的Class是字符串，并且包名是“/”分割，需要替换成“.”，才能获取到对应的Class对象
            String declaredClass = serializedLambda.getImplClass().replace("/", ".");
            Class<?> aClass = Class.forName(declaredClass, false, ClassUtils.getDefaultClassLoader());

            // 第4步  Spring 中的反射工具类获取Class中定义的Field
            field = ReflectionUtils.findField(aClass, fieldName);

        } catch (Exception e) {
            e.printStackTrace();
        }
        // 第5步 如果没有找到对应的字段应该抛出异常
        if (field != null) {
            return field;
        }
        throw new NoSuchFieldError(fieldName);
    }

    public static boolean equalsFiledName(SFunction<?,?> sFunction, String propertyName){
        String fieldName = getFieldName(sFunction);
        return fieldName.equals(propertyName);
    }

}
